The invention relates to a method and a system for post-mortem prolongation of the viability of an organ in donor body.
In some organ donors, the so-called non-heart-beating donors (NHBD), cardiac arrest occurs before the organs can be retrieved. In other donors, the so called Brain Death or Heart Beating (BD or HB) donors, the circulatory system is kept functioning after death of the patient. After the circulatory system has stopped functioning, the organs will lack of oxygen. Moreover, at the moment of death, the organs are at body temperature and therefore in a high metabolic state with the associated high demand of oxygen and nutrients. The lack of oxygen in the still warm organs results in tissue damage. Tissue damage must be prevented, as it has a negative effect on the organ viability after transplantation. Reducing the warm ischemic time in organ donors would reduce tissue damage and result in maintaining a given level of viability for a longer period of time.
Accordingly, time is critical for organ donation. After the decease of a potential donor, generally approval for organ donation needs to be ascertained, before steps for organ extraction may be undertaken. Usual practice is to flush the organs to remove most of the blood from the organs and to cool the organs in order to prolong viability. After flushing, the organs are perfused with a preservation fluid to counteract further tissue damage during transport to the recipients.
Clinical death is determined by brain death or cardiac arrest. In case of death due to cardiac arrest, it is generally legally allowed to start flushing the organs, suited for donation after a period of 5 minutes of so-called “no-touch”. Also after that period, in many cases, immediate explantation of organs is problematic or impossible, for instance because it would form an unacceptable disturbance for grieving relatives.
One known method for prolonging the viability of abdominal donor organs before explantation is in situ perfusion (ISP). Before the organs are taken out, a catheter carrying inflatable balloons is inserted to extend via the femoral artery into the abdominal aorta. Once in place, and after inflation of the balloons, the lower balloon cuts off the lower end of the aorta and the upper balloon cuts off the aorta at the level of the diaphragm. The lower and upper extremities, the torso and the head are thus excluded from perfusion. During perfusion, a perfusate flows out of the catheter between the two inflated balloons, and is forced to flow into the abdominal region, causing the organs to be flushed. The perfusate washes blood out of the organs to prevent clotting and cools the organs, thereby reducing metabolic requirements.
Another known method of prolonging the viability of abdominal organs before explantation from the donor body is extracorporeal membrane oxygenation (ECMO). Arterial and venous cannulae are placed following consent to donate, but prior to withdrawal of support. Circulation of blood is initiated immediately following declaration of death. Blood circulating via the cannulae is cooled and oxygenated before it flows back into the body. The circulation is maintained until the organs are taken out of the donor body. A blood pump drives the circulation.
Although an advantage of extracorporeal membrane oxygenation is, that oxygen is supplied to the organs, the viscosity of cold blood hampers oxygenation and the subsequent flushing of the organs forms an extra step that complicates the procedure and prolongs the time between death of the donor and implantation of the donated organ.